A liquid crystal display panel of a liquid crystal display device does not emit light, so a surface light source needs to be provided by a backlight module. The backlight module includes a direct type backlight module and a side-edge backlight module. A current common direct type backlight module is to dispose a plurality of LEDs arranged in a two-dimensional array under a diffusion plate. Although the direct type backlight module has better brightness uniformity, there is a problem of thick thickness. The current side-edge backlight module has a thinner thickness than the direct type backlight module because a LED strip is disposed on a side of a light guide plate.
However, regardless of the direct type backlight module or the side-edge backlight module, there is a problem that a contrast of a display image is not obvious enough. Although it can be improved by a technique of local dimming, the local dimming still cannot completely correspond to a pattern displayed on a display panel, causing light leakage in a non-pattern display area.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.